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My name is DAVID FINNEY and I am pleased that you have found my  Website. I am an Electrical Engineer who has spent 36 years working as Engineer and Chief Engineer with the General Electric Company(GEC) in the UK. My specialist field was and still is ELECTRICAL VARIABLE SPEED DRIVES and I have written a TEXTBOOK on this subject, see later. During my career I have been envolved in the Design, Development and Supply of Drives from 1KW to 20,000KW. If you are in any way interested in VARIABLE SPEED DRIVES then you should find that this site contains some useful and helpful information.


The principle of these SIMULATORS is to make the Computer operate as though it were the REAL ELECTRONIC SYSTEM in your Laboratory. A System on which you can carry out complex Experiments and Measurements to establish how it will perform under a wide range of circumstances.

The Simulators allow you to :-

Define the SIZE and RATING of the system.

To OPERATE the equipment at any Speed and Load condition.

To MEASURE the values of all the circuit Currents and Voltages.

To see OSCILLOGRAPHIC WAVEFORMS of all the circuit parameters.

To make HARMONIC ANALYSES of these waveforms to quantify the harmonic components.

To plot GRAPHS.

To operate and observe the Drive under CYCLIC LOAD conditions etc etc.

The SIMULATOR therefore allows you to study the system in SAFETY, without any damage to Student or Equipment, in the QUIET of the office rather than in a noisy laboratory.

A particularly important aspect of these Simulators is the ability to set them up to represent systems of ANY SIZE, ANY SPEED, and ANY VOLTAGE and with any degree of SIMPLICITY or COMPLEXITY. The Simulator will give TRUE RESULTS in all cases taking into account :-- power losses and efficiencies, circuit reactances, convertor firing angles, commutation and overlap, slip, inverter switching frequencies, etc etc

These Simulators are useful to :- College and University Lecturers and to Suppliers and Users of Electrical Drives.

To teach the Technical understanding of these Drive Systems.

To enable SELF-LEARNING by the students.

To teach students in the SAFETY and QUIET of the classroom.

To carry out Experiments on the chosen Drive.

To allow detailed study of the Circuit WAVEFORMS.

To enable operation of the different systems to be compared.

To carry out Research Work on such Drives.

To provide an ECONOMIC means of studying these Drive Systems.

To select the BEST DRIVE for a particular Application.

To obtain Performance Information for Customers.

To help you understand HOW the DRIVE WORKS.

To help you decide on the RATINGS and SPECIFICATIONS of Motors, Convertors, Transformers and Cables etc..

To assess the degree of POWER FACTOR CORRECTION needed.

To assess the Current and Voltage HARMONICS applied to the Motors.

To estimate the Harmonic Currents injected into the Mains Supply.

To assist in the TRAINING of Sales Engineers and Maintenance Technicians.

To decide the ENERGY SAVINGS which can be made by using Variable Speed Drives.

To enable you to MODEL the REAL Drive or System.

With these Simulators you can :-

RUN the DRIVE SYSTEM using the computer Keyboard or Mouse to input Instructions and with all Measurements being displayed on the computer's colour monitor.

RUN the DRIVE under CLOSED LOOP or OPEN LOOP control so that the Drive's reaction to input changes can be observed.

EASILY ALTER the Power Rating, Speed, Voltage, Motor Parameters, System Efficiency etc., so that ANY DRIVE can be studied.

SEE VISUALLY the detailed SWITCHING OPERATIONS of the power switches, in slow motion, synchronised to the Drive's running speed.

CARRY OUT EXPERIMENTS on the Drive and see the values and the WAVEFORMS of all the currents and voltages and even the ShaftTorque.

AUTOMATICALLY PRINT onto paper a Full Range of GRAPHS, WAVEFORMS, HARMONIC ANALYSIS CHARTS, DYNAMIC PERFORMANCE Plots and the OPERATING SCREENS to Laser, Dot-Matrix or Inkjet Printers in black/white or COLOUR(for Windows Versions).

See all of the Drive's WAVEFORMS including the effects of harmonic ripple, beating, commutation overlap, PWM switching etc., under ANY CONDITION of Speed and Torque.

Assess the HARMONIC CONTENT of the Waveforms to an accuracy far above that obtainable by traditional methods because the Waveforms analysed take ALL KNOWN EFFECTS into account.

Assess the ENERGY COSTS and SAVINGS which can be made by using a Variable Speed Drive to drive a FAN, PUMP or COMPRESSOR instead of using VALVES or DAMPERS to control the flow.

Find out how a Drive will perform against a CYCLIC Load involving the ACCELERATION and RETARDATION of an INERTIA Load. Peak, Mean and RMS values of all the variables are plotted against time and loadings requiring up to 3 times Rated Current can be accepted. Regenerative and Resistance BRAKING are catered for.

PRINT all GRAPHS, WAVEFORMS, HARMONIC ANALYSES, DYNAMIC PERFORMANCE Plots and OPERATING SCREENS to .IMG and .TIF Disc Files (in MSDOS Versions) and to the CLIPBOARD (in the WINDOWS Versions) so that they can be quickly transferred into WORDPROCESSOR or DESK TOP PUBLISHING Documents.